On the brink: Sixth mass extinction that will eradicate 75% of life is drawing close

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On the brink: Sixth mass extinction 'that will eradicate 75% of life on Earth is drawing closer'

By Daily Mail Reporter
Last updated at 3:24 PM on 3rd March 2011

Earth may be on the brink of a sixth mass extinction on the scale of the apocalyptic event that wiped out the dinosaurs, a study claims. The researchers say that unless action is taken now to reverse the harmful effects of human activity on eco-systems, a full-blown mass extinction could occur within a few centuries.

Recovery from such an event, which could eradicate more than three-quarters of all life on Earth, may then take millions of years.

Only five previous mass extinctions have occurred in the last 540million years.

They are classified as the Ordovician event (443million years ago); the Devonian event (359million years ago); the Permian event (251million years ago); the Triassic event (200million years ago) and the Cretaceous event (65million years ago).

The last mass extinction, thought to have been triggered by a meteor impact in Mexico, was marked by the loss of 76 per cent of species including the dinosaurs.

A new study of mammal populations raises the alarming prospect of a sixth mass extinction, this one a direct result of the effect humans are having on the planet. Scientists in the U.S. compared extinction rates from the fossil record with the speed at which mammals are vanishing today.

Within the past 500 years, it is estimated that at least 80 species of mammals have become extinct out of a starting total of 5,570 species. This compares with an average extinction rate for mammals of less than two species disappearing every million years.